Mycobacteria owe their success as pathogens to their ability to persist long periods within host cells in asymptotic,latent forms before they opportunistically switch to the vimlent state.The molecular mechanisms underlying the transition into dormancy and emergence from it are not clear.Data will be presented demonstrating that Mycobacterium spp.sporulates.In fresh media,the spores germinated into vegetative cells and reappeared in the stationary phase,via endospore formation.They showed many of the usual characteristics of well-known endospores.Homologs of well-known sporulation genes were detected in mycobacterial genomes,some of which were verified to be transcribed during appropriate life cycle stages.Our data opens for the possibility that mycobacteria might use sporulation as a strategy for dormancy and persistent pathogenicity,as well as for survival during external stress.